Hydrophone mounting



y 1951 L. BATCH-ELDER 2,560,066

HYDROPHONE MOUNTING Filed Nov. 27, 1948 2 Sheet-Sheet 1 0 FIG. 1 I;

FIG. 2

35 INVENTOR LAURENCE Ram/ELDER RNEY y 10, 1951 L. BATCHELDER I 2,560,066

7 HYDROPHONE MOUNTING Filed Nov. 27, 1948 2 Sheets-Sheet 2 INVEYNTOR LAURENCE aqrcwewsn Patented July '10, 1 9 51 HYDROPHONE MOUNTING Laurence Batchelder, Cambridge, Mass., assignor to Raytheon Manufacturing Company, a corporation of Delaware Application November 27, 1948, Serial No. 62,327

6 Claims. (Cl. 177-386) This invention relates to hydrophone mount- .ings and more particularly to means for mounting a hydrophone in the skin of a ship or the like It is a further object to devise such a mount- 1 ing which will hold the hydrophone in the desired position for normal operation, and which has means constantly ready to prevent the hydrophone from being torn away in the presence of abnormal shock.

It is a further object to devise such a mounting which provides a smooth unbroken surface to the surrounding water and sacrifices none of the ad vantages heretofore available.

Other and further objects of the invention will become apparent from the description of certain embodiments thereof which follows, reference being made to the accompanying drawing, wherein:

- Fig. 1 is a side elevation partly in section of a hydrophone mounting in accordance with the invention;

' Fig. 2 is a bottom view of Fig. 1;

Fig. 3 is a side elevation partly in section of another embodiment of the invention; Fig is a modification of Fig. 1 Fig. 5 is'a modification of Fig. 3; and Fig. 6 is a vertical section showing a typical hydrophone of the general type with which the invention concerned.

Referring now to Figs. 1 and 2, a hydrophone I 01 generally cylindrical shape has a diaphragm II at one end thereof. The diaphragm is sensitive to pressure waves, as is well known to those skilled in the art. The hydrophone is further provided around its sides at a distance from the diaphragm end with .a raised circumferential projection I2 which is used as a keeper to prevent the hydrophonefrom being torn away in the presence of a wave of abnormally large 'amplit'ude. Thediameter of the hydrophone is reduced at I3 in the region between the keeper I2 and the diaphragm II. A rubber annulus I4 is fitted over and bonded to this portion I3 of the side wall of'the hydrophone. This annulus is flush at one side I5 with the face of the diaphragm II, and the other side I6 does notreach as far as the keeper I2, but rather there is a space I! between the keeper and the rubber annulus. A metallic annulus I8 surrounds and is tightly bonded to the rubber annulus I4. The metallic annulus is of similar axial width to the rubber annulus and is provided with aradially outwardly projecting flange I9 at the side thereof nearer to the keeper I2. This fiange is used for mounting the hydrophone in an opening in the skin of a ship or other suitable wall, as will now be described.

The wall 2| wherein the hydrophone is mounted, which may, for example, be the skin of a ship, is provided with a ring 22 of substantially greater mass than the wall material and preferably welded thereto as at 23, 24. The mass ring 22 serves to a certain degree to prevent vibrations present in the wall 2| from reachin the hydrophone 'IO. It has been found, however, that this ring does not function perfectly, and that some vibrations which are present in the wall 2| continue to reach the hydrophone. The flange I9 is clamped against a first shoulder 21 on the mass ring 22 by means of a clamping ring 25 which is threadedly fitted into the mass ring. The clamping ring 25 fits loosely about the metallic annulus I8, and a gasket 26 is provided at the "side of the flange I9 nearer the mass ring 22. The mass ring 22 is provided with the first shoulder 21 by reducing the inner diameter thereof bya suitable amount at a distance in from the outer surface of the wall 2I. This reduction in inner diameter is such that the keeper I2 of the hydrophone I0 fits loosely in the portion of reduced diameter when the flange I9 rests against the first shoulder 21. The mass ring 22 is provided with 'a secondshoulder 28 formed by further reducing the inner diameter thereof at the inner side above the keeper I2. The shoulder 28 and the flange I9 now provide a recess 29 wherein the keeper I2 loosely rests. The keeper I2 is not in contact with any part of this recess so long as the rubber annulus I 4 is not seriously deformed, as it might be by a wave of abnormally great amplitude.

.Should the rubber annulus I4 be so deformed;

the keeper I2 would come in contact with either the second shoulder 28 or the flange I9, and the hydrophone could not be torn away. The hydrophone In is, however, normally supported only by the rubber annulus I4.

As has been already set forth, the hydrophone is sensitive to pressure wave vibrations arriving at the diaphragm' II. Vibrations in the hull, or wall 2| and the mass ring 22 in the direction of a line 'normal to the diaphragm normally tend to move the body of the hydrophone, and with it the face of the diaphragm, toward and away from the water, thereby creating pressure waves on the diaphragm. The hydrophone is highly sensitive to such waves. However, these vibrations are transmitted to the hydrophone Hi as shear waves in the rubber of the annulus l4. It is well known that rubber offers a high degree of attenuation to shear waves. Vibrations in the hull, or wall 2|, in directions parallel to the surface of the diaphragm l I, may be transmitted by the rubber annulus l4 as compressional waves, the rubber being compressed thereby, but the diaphragm is moved parallel to its surface by such waves, and not toward and away from the water, so that the hydrophone I is comparatively insensitive to such vibrations. From another point of view, it may be said that the rubber ring l4 prevents hull vibrations from moving the hydrophone in such a fashion as to cause it to be actuated as a'velocity device. The vibrations in the wall 2| which would normally tend to move the body of the hydrophone toward and away from the water cause velocity actuation of the hydrophone, whereas normally the body of. the

hydrophone is still and actuation is effected by causing pressure changes on the diaphragm. The present invention thus eliminates the very source of spurious signals.

It will be noted that the diaphragm I I is maintained in direct contact with the water or other medium outside the wall 2|. In fact, the face of the diaphragm H is in register or flush with the outer surface of the hull, or wall'2l so that this surface is not broken and does not interfere with the flow of water by it.

The arrangement shown in Fig. 1 is designed for mounting the hydrophone from outside the wall 2|. In the case of a ship or the like, this would require that the ship be dry-docked. The

arrangement shown in Fig. 3 is designed for in-' board mounting. With this arrangement, the hydrophone could, under the proper circumstances, be installed without resorting to drydocking. In the arrangement of Fig. 3, the hull ring 32 is provided with one shoulder 33 at the outer side thereof and is internally threaded at the inner side 34 thereof. The normal inside diameter of this hull ring is of sufficient size to accept the flange I6 of the hydrophone mounting freely with the flange resting upon the shoulder 33. A gasket 35 is provided between the flange and the shoulder. A clamping ring 36, threaded at the upper end 31 of its outer periphery, fits into the hull ring 32 and is threadedly engaged therewith to hold the flange i9 against the shoulder 33. This clamping ring has a portion of large inside diameter at the lower end 38 thereof, which portion fits loosely around the keeper l2, and the remainder is of smaller diameter, providing a shoulder 39 over but not touching the keeper. The shoulder 39 and flange is cooperate to provide again the recess 29 wherein the keeper I2 rests.

In Figs. 1 and 3 the clamping rings 25 and 36, respectively, are threadedly engaged with the hull rings 22 and 32, respectively, being put in place by means of a spanner wrench or the like which engages suitably placed holes 4| in the clamping rings. In Figs. 4 and the clamping rings 25 and 36 are replaced by clamping rings 42 and 43, respectively, of a different form, which are attached to the bull or mass rings 44 and 45, respectively, by means of screws 46 or bolts 41, as may be suitable.

Referring particularly to Fig. 4, the mass ring. ring 44 differs from the mass ring 22 of Fig. 1 only in that the inner diameter thereof is increased at the front or outside surface to provide an additional shoulder 48 against which the clamping ring 42 rests, and into which the clamping screws 46 are driven.

Referring now particularly to 5, the mass ring 45 differs from the mass ring 32 of Fig. 3 in that it is shorter, while the clamping ring 43 is provided with a portion 43 of expanded diameter at the top thereof. This portion 43 of expanded diameter overhangs the top surface 5| of themass ring 45, and the bolts 41 are driven P into the mass ring through this top surface. In

all other respects, the'arrangements shown in Figs. 4 and 5 are similar to the arrangements shown in Figs. 1 and 3, respectively.

The transducer it may have the internal structure shown in Fig. 6. The casing is made of a generally cylindrical portion 53 whereon the keeper I2 is found, a top closure 54 which is attached to the cylindrical portion 53 by bolts 55, for example, and a bottom closure 56 which .is threadedly engaged on the cylindrical portion 53, and includes the diaphragm H. The cylindrical portion 53 is internally threaded at a portion 51 intermediate the ends thereof, and a pressure ring 56 is engaged in the threads. The pressure ring has a circular boss or raised portion 59 on the lower surface thereof for a purpose which will presently be explained. The diaphragm H is formed as an integral part of the lower closure 56 by removing an annular portion of the inner side of the closure at or very close to the side wall to provide a thin rim 6|. The diaphragm I l vibrates somewhat as a piston supported by this thin rim. Crystals 62 and 63 are clamped between the diaphragm II and a clamping plate 64. The boss 53 is in contact with the upper surface of the clamping plate 64, and the clamping pressure is determined by the clamping ring 56, which may be turned by a spanner wrench or the like, engaging holes 65 therein.

The crystals 62 and 63 are each provided with two electrodes 66 and 61, one on each side thereof, through which electrical signals correspondsages 13 and 14 through which the conductors H and 12 pass. The crystals 62 and 63 are shown connected in parallel to these. conductors, but it will be appreciated by those skilled in the art that the connection may be in series if desired.

The details of the hydrophone shown in Fig. 6 are shown merely to illustrate the type of hydrophone with. which theinvention is concerned, namely, a hydrophone which is sensitive to pressure waves arriving at the diaphragm l l It should be definitely understood that other chanacteristics may be varied in any manner desired. For example, more crystals may be used, other types of electromechanical converting devices may be used, and various mechanical arrangements of the parts too numerous to discuss here may also be used. Many other modifications-and variations of the invention will occur to those skilled in the art, and it is accordingly intended that the claims that follow should not be limited by thedetails of the embodiments of the invention disclosed herein. but only by the prior art.

What is claimed is: 1. In combination. a hydrophone having a pressure wave sensitive diaphragm at the front and a substantially rigid cylinder supporting said diaphragm across an end thereof, a resilient perimetric cylindrical element fastened at its inner cylindrical surface to the outer side surface of said cylinder, and a substantially rigid perimetric cylindrical element secured about and bonded to said resilient element, said cylinder being otherwise telescopically fitted loosely within said rigid element, said resilient element being of a material which strongly attenuates shear waves, the dimensions of said cylinder, said resilient element and said rigid element being chosen so that said resilient element is not anywhere compressed between the outer surface of said cylinder and the inner surface of said rigid element, the only normal support for said hydrophone in said rigid element being afforded by bonding of said resilient element to each of said outer surface of said cylinder and said inner surface of said rigid element, and said resilient element having no support members projecting thereinto.

2. In combination, a hydrophone having a pressure wave sensitive diaphragm at the front and a substantially rigid cylinder supporting said diaphragm across an end thereof, a rubber perimetric cylindrical element bonded at its inner cylindrical surface to the outer side surface of said cylinder, and a substantially rigid perimetric cylindrical element surrounding said rubber element and bonded'. thereto, and spaced from said hydrophone by said rubber element, said cylinder being otherwise telescopically fitted loosely within said rigid element, the dimension of said cylinder, said rubber element and said rigid element being chosen so that said resilient element is not anywhere compressed between the outer surface of said rigid element, the only normal support for said hydrophone in said rigid element being afiorded by the bonding of said rubber element to each of said outer surface of said surface and said inner surface of said rigid element, and said resilient element having no support members projecting thereinto.

3. In combination, a wall having a cylindrical opening therein, a hydrophone having substantially rigid side walls and a pressure wave sensitive diaphragm disposed in said opening with said diaphragm flush in the surface of said wall, said side walls being cylindrical, of lesser diameter than said opening, and telescopically fitted therein, and a resilient hollow cylindrical member bonded only at its inner and outer cylindrical surfaces to the inner cylindrical surface of the opening in said wall and said side walls of said hydrophone, respectively, filling the space between said hydrophone and said wall, said resilient member being of a material which strongly attenuates shear waves, the dimensions of said opening, said resilient member and the cylinder providing said side walls being chosen so that the resilient member is not anywhere compressed between said side walls and the material of said wall defining said opening, the only normal support for said hydrophone in said wall being afforded by said bonding, and said resilient member having no rigid support members projecting thereinto.

4. In combination, a hydrophone having a pressure wave sensitive diaphragm at the front and a substantially rigid cylinder supporting said diaphragm across an end thereof, a resilient perimetric cylindrical element fastened at its inner cylindrical surface to the outer side surface of said cylinder, a substantially rigid perimetric cylindrical element secured about and bonded to said resilient element, said cylinder being otherwise telescopically fitted loosely within said rigid element, said resilient element being of a material which strongly attenuates shear waves, the dimensions of said cylinder, said resilient element and said rigid element being chosen so that said resilient element is not anywhere compressed between the outer surface of said cylinder and the inner surface of said rigid element, the only normal support for said hydrophone in said rigid element being afforded by. bonding of said resilient element to each of said outer surface of said cylinder and said inner surface of said rigid element, and said resilient element having no support members projecting thereinto, and a radially outwardly extending flange on said rigid element whereby said hydrophone may be secured to the skin of a ship.

5. In combination, a hydrophone having a pressure wave sensitive diaphragm. at the front and a substantially rigid cylinder supporting said diaphragm across an end thereof, a resilient perimetric cylindrical element fastened at its inner cylindrical surface to the outer side surface of said cylinder, a substantially rigid perimetric cylindrical element secured about and bonded to said resilient element, said cylinder being otherwise telescopically fitted loosely within said rigid element, said resilient element being of a material which strongly attenuates shear waves, the dimensions of said cylinder, said resilient element and said rigid element being chosen so that said resilient element is not anywhere compressed between the outer surface of said cylinder and the inner surface of said rigid element, the only normal support for said hydrophone in said rigid element being afforded by bonding'of said resilient element to each of said outer surface of said cylinder and said inner surface of said rigid element, and said resilient element having no support members projecting thereinto, a radially outwardly extending flange on said rigid element, a radially outwardly extending keeper flange on said supporting cylinder in a region removed from the resilient element, a wall having an opening in which said rigid element is mounted by said radially outwardly 'extending flange, said wall bearing an element having a groove wherein said keeper flange reposes out of contact with said grooved element.

6. In combination, a wall having=a cylindrical opening therein, a hydrophone having substantially rigid side walls and a pressure wave sensitive diaphragm disposed in said opening with said diaphragm flush in the surface of said wall, said side walls being cylindrical, of lesser diameter than said opening, and telescopically fitted therein, and a resilient hollow cylindrical member bonded only at its inner and outer cylindrical surfaces to the inner cylindrical surface of the opening in said wall and said side walls only of said hydrophone, respectively, filling the space bekeeper flange mounted on said cylindrical side walls at a region removed from the resilient member, and means rigidly mounted on said wall providing with said wall a recess wherein said flange jfits, said recess being larger than said flange and having its wall surface normally free from contact therewith, the material of said 5 means being positioned to restrain said hydrophone trom complete removal from said wall in the event said resilient member is stressed by a wave which otherwise might tear away said resilient member, and thereby to prevent execs-' sive stress on said resilient member.

LAURENCE BATC'HELDER.

REFERENCES CITED The following references are of record in the tile 0! this patent UNITED STATES PATENTS 

